The present invention relates to a heat-radiation heat pipe particularly used in an information electronic appliance, or the like, and a method for processing the same.
In information electronic appliances such as a notebook type personal computer, etc., the heating density of electronic parts such as an MPU, etc., becomes very high with development of complexity while satisfying demands for reduction of weight and thickness. To comply with the demands, it has become to use a thin plate type heat pipe for radiation of heat from the aforementioned heating parts.
To finish the heat pipe to be thin, it is necessary not only to reduce the required heat flow rate in the vapor passage of the operating fluid substantially to a limit, but also to put a core at the time of processing to control the accuracy of the inner area and to finish the thickness of the container material to be very small.
However, even in the case where the above-mentioned ideas are executed, there is naturally a limit to the reduction of thickness because the container must bear both mechanical pressure from the outside and inner pressure accompanying the two-phase change of vapor and liquid and because some liquid reservoirs caused by the starting characteristic of the heat pipe are generated partially in the axial direction of the heat pipe to thereby cause increase of heat resistance. Accordingly, conventionally, no material having a smaller thickness than about 1.5 mm could be provided.
The present invention is designed to solve the aforementioned problem and it is an object of the present invention to provide a heat pipe in which a good effect can be obtained even in the case where the heat pipe has a thickness not larger than 1 mm, and a method for processing the same.
To solve the aforementioned problem, according to the present invention, a core, which has been generally taken in or out whenever processing is performed, is designed to be left in the heat pipe whenever the heat pipe is processed, as a structure optimum to a wick, which is put in a heat pipe for circulation of an operating fluid. Accordingly, it is made possible to provide a very thin heat pipe having a thickness not larger than 1 mm and excellent both in heat transport ability and in heat resistance property.
That is, the invention provides a heat pipe comprising a flat container, and a member selected from a rod, a plate and a mesh, the member being fixedly arranged between narrow walls of the container so that space is provided in the inner circumference of the container both in the direction of width and length of the container; another embodiment of the invention provides a heat pipe comprising: a first pipe; at least one second pipe having a relatively small diameter and a relatively short length compared with the first pipe, the at least one second pipe being inserted in the first pipe so as to be fixed substantially at a center portion of the first pipe, the first and second pipes being flattened; and an operating fluid put into the first pipe, the heat pipe being sealed at its opposite ends; in a heat pipe according to the present invention the second pipe may be formed from a mesh or a braided wire; furthermore, in a heat pipe according to the present invention, the second pipe is deformed like a pair of spectacles in section; in a heat pipe according to the present invention, the inside of the first pipe is grooved; and in a heat pipe according to yet another embodiment of the present invention, the inside of the container is grooved or provided with mesh.
Further, in accordance with the present invention, provided is a method for processing a heat pipe by using a first pipe, a second pipe having a relatively small diameter and a relatively short length compared with the first pipe, and an arbor, comprising the steps of inserting at least one second pipe in the first pipe so as to be temporarily fixed substantially at a center portion of the first pipe by using the arbor, pressing the first pipe to flatten the first pipe to thereby fix the second pipe to the inner wall of the first pipe, taking out the arbor; putting an operating fluid into the first pipe, and sealing end portions of the first pipe; furthermore, provided is a method for processing a heat pipe by using a first pipe, a second pipe having a relatively small diameter and a relatively short length compared with the first pipe, and an arbor, comprising the steps of inserting at least one second pipe in the first pipe so as to be temporarily fixed substantially at a center portion of the first pipe by using the arbor, pressing the first pipe to flatten the first pipe to thereby fix the second pipe to the inner wall of the first pipe, taking out the arbor; pressing the second pipe again to deform the second pipe to be like a pair of spectacles in section while leaving at least an injection portion, putting an operating fluid into the first pipe, and sealing an end portion of the first pipe; also, provided is a method for processing a heat pipe by using a first pipe, a second pipe having a relatively small diameter and a relatively short length compared with the first pipe, and an arbor, comprising the steps of inserting at least one second pipe in the first pipe so as to be temporarily fixed substantially at a center portion of the first pipe by using the arbor, pressing the first pipe to flatten the first pipe to thereby fix the second pipe to the inner wall of the first pipe, taking out the arbor, processing the second pipe to flatten the second pipe while leaving at least an injection portion is left, putting an operating fluid into the first pipe, and sealing an end portion of the first pipe.
Further, in yet another embodiment of the present invention, provided is a heat pipe comprising a flat container, and a depressed wall, in which the depressed wall is formed by depression of at least one surface substantially in the center portion so that space is provided in the inner circumference of the container both in the direction of width and length of the container; furthermore, provided is a heat pipe used in an electronic appliance, wherein one end of a container is throttled as an operating fluid injection hole, the other end of the container is pressed or welded so as to be sealed, at least one surface of the container forms a depressed wall having a smaller length than the axial length, the depressed wall is brought into contact with a counter wall so that a loop-like heat pipe is formed by the depressed wall and the inner wall of the container, and the injection hole is sealed after an operating fluid is injected; in moreover, in a heat pipe according to the present invention, the operating fluid is enclosed by an amount not smaller than 25% of an inner volume of space of the container; also, in a heat pipe according to the present invention, at least a part of the inside of the container is provided with a wick grooved or formed of mesh; and in addition, a heat pipe according to the present invention, at least a part between the depressed wall and a counter wall is welded.
Further, provided is a method for processing a heat pipe, wherein at least one surface of a round rod-like heat pipe is depressed substantially at a center portion thereof when or after the round rod-like heat pipe is pressed so as to be flattened; in a method for processing a heat pipe according to the present invention, the heat pipe is kept at a temperature not lower than 50 C.; also, provided is a heat pipe characterized in that the heat pipe comprises a flat first pipe, and at least two depressed walls formed by pressing a flat surface of the first pipe in the axial direction so that operating fluid passages are formed by the depressed walls; and in a heat pipe according to yet another embodiment of the present invention, a wick material is provided in the operating fluid passages formed by the depressed walls except operating fluid passages located in end portions.